L11-C76 is a ribsomal binding protein domain that stimulates the rate of protein synthesis. It binds to a 57 nucleotide RNA fragment which is at the center of GPase activity in the ribosomal. The first goal of this project is to determine the structure of the free protein and the structure of L11-RNA complex. Multidimensional NMR spectroscopy has been used to obtain complete signal assignments of the L11 free in solution and complexed with the rRNA fragment. A high resolution structure of the free protein has been determined, and regions of the protein that interact with the RNA have been identified. Determination of the structure of the bound protein is underway. The significance of this work is the information that it will provide about interaction of proteins and ribosomal RNA at the atomic level. To date there is virtually no detailed structural information about protein complexes with large rRNA fragments from either X-ray diffraction or NMR.